A new ATM service category, the available bit rate service, has been introduced in the ATM Forum. It dynamically allocates available bandwidth to users by controlling the flow of user traffic with feedback. The Forum has ratified the rate-based flow control framework for the support of this new service. We provide a recipe for designing rate-based feedback schemes demonstrating the rich variety of available switch mechanisms. Each aspect of the feedback control loop mechanism is explored in detail and several available choices are investigated. Two example switch mechanisms are provided that illustrate the rate-based control design principles. The ability of these mechanisms to support the desired objectives of an ABR service is compared using a reference network configuration. Simulation results show that the rate-based framework allows a great degree of architectural flexibility in the design of switch mechanisms. The rate-based framework provides switch vendors sufficient flexibility to choose a mechanism among several available options, based on their performance requirements and cost budgets.
展开▼
